Arrangement for generating electric oscillations



Oct. 18,1927. f 1,545,557

0. VON BRONK ARRANGEMENT FOR GENERATING ELECTRIC OSCILLATIONS Filed F551). 26, 1924 v ambdmboz OTTO VON BRONK 3513 his ("1 0M445 Patented Oct. 18, 1927.

(UNITED STATES PATENT OFFICE...

OTTQ'voN BRONK, or BERLIN, GERMANY, ASSIGNQR 'ro GEsELLscHAr'r 'Fi T R DRAHT rosETELEGnAPiii-E M. BIHJ, on BERLIN, GERMANY, AconronA'rIoN on GERMANY;

ARBANGE'MENT FOR GENERATING ELECTRIC OSCILLATTONSJ Application filed February 26, 1924, Serial No. 695,158, and in Germany March 10, 1923.

This invention relates to an arrangement for generating high frequency electric oscillations such as are used in radio work.

An object of the invention is to provide a generator of high frequency oscillations which comprises a source of audio frequency and means for tuning and then amplifying a harmonic of the audio frequency wave, the said harmonic being the radio frequency de sired.

This and further objects will be apparent from the following description when taken with the accompanying. drawing in which the single figure illustrates a simple embodiment of the invention.

It is a fact that if a telephone receiver connected in circuit with a telephone transmitter in the usual manner, be placed near the transmitter in such a way that sound waves sent out by the receiver diaphragm act directly on the transmitter, undamped oscillations will be produced, resulting usually in an audible howl. This fact up till-now has been of no importance in the production of radio frequency waves because the pro duction of waves of more than 2000 cycles per second causes difiiculties because of the mechanical inertia of the receiver and transniitter.

According to the present invention radio frequency oscillations can be produced by means of the microphone-buzzer in such a way that the frequency generated by the microphone-buzzer acts on an oscillatory c1rcuit which is tuned to a harmonic of the audio frequency, which harmonic may be the radio frequency desired. This radio frequency circuit may then be coupled to the gridfilament circuit of an amplifier valve, in the plate-filament circuit of. which is an oscillatory circuit tuned to the frequency of that harmonic. By this means undamped oscillations of highest frequencies can be generated without regeneration or a coupling reaction of the plate-filament circuit to the grid circuit being necessary as in the normal vacuum valve generator. As the frequency of the microphone-buzzer can be altered as required by adjoining acoustic resonators the frequency of the harmonics can also be altered correspondingly.

The drawing shows schematically one example of the present invention. The alterations of current caused by microphone 1, which are led thru the primary of transformer 2, the secondary of which is connected to buzzer 3, act on microphone, 1, and the system operates according to the principle of the regenerative microphone-buzzen In the audio frequency circuit the oscillatory circuit 4 tunedto a harmonic is inserted and connected to the grid-filament circuit of the valve 7 by the radio frequency coupling 5. An adjustable auxiliary voltage may be applied to. the grid 6 in order to work ona suitable part of the valve characteristic curve. In the plate-filament circuit of valve 7 there is another oscillatory circuit 8, tuned to the same harmonic, which may be coupled,

for example, to an aerial 9. Of course the frequency can, if necessary, be further multiplied in any of the ways known.

It is essential that the coupling between in which a telephone transmitter and re ceiver are so connected that audio frequency oscillations are produced thru regeneration, a second oscillatory circuit tuned to a harmonic of the audio frequency and -connected in said first circuit, and means for leading off the said harmonic loosely coupled to said second circuit so as to pass only the harmonic.

2. In combination, a microphone, a magnetic receiver placed in acoustic relation therewith and electrically coupled thereto by means of an iron core transformer for the production of alternating current of fundamental frequency, a resonant circuit including an air core transformef in series with one of the transformer circuits and tuned to a harmonic of the'fundamental frequency, and a vacuum tube amplifier tuned to the harmonic'coupled to the air core transformer.

3. The combination with means to generate a fundamental frequency comprising two coupled circuits, a variable impedance element and an electro-magnetic yibratory 4. Means to generate a radio frequency element in physically cooperative relation under audible control comprising a mlcroand electrically connected one in each of phone-buzzer tuned to an audio frequency, 10 said coupled circuits, of a resonant circuit and a resonant circuit tuned to a radio fretuned toa harmonic of the fundamental fre quency harmonic of the audio frequency quency connected in one of said coupled circonnected in the microphone-buzzer circuit cuits. 7' j OTTO VON BRONK. S 

